Since World War II the chemical industry has grown to the point where there are over 35 million metric tons of hazardous wastes being generated. Large quantities of these wastes contain synthetic halogenated materials such as found in dielectric fluids, flame retardants, refrigerants, heat transfer fluids, lubricants, protective coatings, pesticides, and herbicides. Furthermore, it is well known that both the petroleum industry and the coal industry contribute many more millions of metric tons of hazardous chemical wastes to be disposed of which contain obnoxious organic compounds. Many of these materials are non biodegradable or recalcitrant, i.e., difficult to biodegrade.
Among the most hazardous and toxic of materials known to man are the dioxins. The most toxic of these materials is represented by the formulation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). They are a hazard in land, water or air, no matter where, and are the most controlled toxic substance under Federal, State, and Municipal laws. Regulating the dioxins are subject to a no detection limit, and the detection limit of dioxins is presently 2 parts per trillion (ppt). Dioxins are created out of any number and variety of materials primarily as by-products in other manufacture of chemicals such as insecticides, e.g. 245T, biocides such as hexachlorophene, chlorobiphenols, and by incineration of halogenated organic wastes. Polychlorobiphenyls (PCB's) are also subject to stringent limits generally less than 2 parts per billion (ppb). The PCB's are introduced into the environment as a result of their use in electrical equipment. The dioxins and PCB's are by far the most difficult toxic material to remove and destroy. They are, for all intensive purposes, non-biodegradable.
Landfills have been used as disposal sites for as much as 80 percent of the hazardous waste, out of the 35 million tonnes per year, which are under Federal Regulation in the estimated 270 landfills in the United States. Many of these contain dioxins and PCB's . When they are present, with other hazardous chlorinated organic compounds, they find their way into the leachates which are formed over the course of time by a process of liquifaction the contents of the landfill.
These leachates must be collected and treated to meet the standard set by the Federal, State, and Municipal laws to make them environmentally acceptable for disposal in the ecosphere.
Various methods and techniques have been proposed and used for disposing of and/or treating leachates or chemical wastewaters containing dioxins, PCB's and related products to make them compatible with the environment. Among the processes or technologies either proposed or employed are incineration on land and at sea, plasma arc, biodegradation, chemical dechlorination, ion exchange, filtrations of various kinds, electrolysis, carbon/resin adsorption, pyrolysis, molten salt bed reactors among others. In spite of all the effort and money being spent, no technology has evolved which is both economically and technically satisfactory for removing dioxins, PCB's and other recalcitrant chlorinated organic compounds from wastewater so it may be discharged into streams, rivers, lakes, or the sea without contamination of such bodies of water.
The present state-of-the-art for treating chemical process wastewaters and chemical landfill leachates containing dioxins and PCB's involves employing a series of process steps whch are difficult to manage and/or operate economically with results that meet the stringent effluent restrictions imposed by Federal and State law.
Accordingly, it is an object of this invention to provide a new and improved process for removing dioxins, PCB's and other chlorinated organic chemical compounds from leachates and chemical wastewaters in an economical and efficient manner to produce an effluent which has less than 2 ppt dioxins and 2 ppb PCB's and is acceptable in the ecosphere.